The invention relates to a high speed electromagnetically actuated electromechanical switching unit. The switching unit is amenable to an electric remote control function, similar to a relay. In addition, the switching unit is amenable to local manual control.
The switching unit is characterized by its extremely fast operation. The unit requires less than one-half cycle of a 60 hertz AC line to turn ON, i.e. less than 0.008 seconds. The unit likewise requires less than one-half cycle of a 60 hertz AC line to turn OFF.
A single armature plunger reciprocally shuttles between magnetic paths. A pair of coils are energizable to create magnetic fluxes having portions of their linkage paths in common, including through the plunger. When either coil is energized, a flux path is created around that coil through the plunger, and another flux path is created around both coils through the plunger. The ratio of the permeances of the two paths is controlled such that one path always overpowers the other, to insure plunger movement in either direction to actuate bistable snap blade electrical contact means. The plunger is held in place by the snap blade until the net magnetic gradient overcomes the mechanical gradient of the snap blade, whereafter the system avalanches and is committed to switch.
In the preferred embodiment, the switching event is committed at 5 milliseconds after the application of current to the coil, and may be less, depending upon the phase of applied AC power. The switching event is completed in another 5 milliseconds, i.e. the contacts are closed, including bounce. Plunger movement in either direction occurs within 1 millisecond.
High speed operation of the switching unit is enabled by various features in combination. The mass of moving parts is minimized by the use of a single armature that shuttles between two magnetic paths. The contact system is of reduced mass and flexes about one end, thereby minimizing the inertia of a moving snap blade. A double Euler beam snap blade has a pair of cantilever arms extending towards each other to engage the armature plunger in the gap therebetween, which provides centering balance on the plunger which prevents lateral bias, which in turn reduces friction to thus increase speed.
The switching unit operates on either AC or DC current. The unit consumes no power when ON or OFF, and is mechanically held ON and OFF with zero holding energy. The unit is further characterized by its overall compactness and by low cost.